The invention is based on a directional control valve which is used for the load-independent control of a hydraulic load in terms of direction and speed, comprising a control piston (22) which can be displaced axially in opposite directions from a central position in a piston bore (21) of a valve housing (20). with which the pressure medium paths can be controlled between a feed chamber (27), to which pressure medium can be fed from a pressure medium source, a discharge chamber (32, 33), via which pressure medium can be led away to a tank, and two load chambers (28, 29), which has first fine control grooves (55) for opening a connection between a load chamber (28, 29) and the feed chamber (27) under control, and second fine control grooves (56) for opening a connection between a load chamber (28, 29) and the discharge chamber (3, 33) under control, and via which, in the central position, there is a restricted relief connection from a load chamber (28, 29) to the discharge chamber (32, 33).
In practice, in the control piston of the variant with a relieved central position, as compared with the control piston which, in the central position, shuts off the load chambers present, the second fine control grooves are lengthened to such an extent that, even in the central position of the control piston, they project into the load chambers. The disadvantage in this case is that, in the event of valve actuation, at the start of opening the first fine control grooves, the flow cross section between the feed chamber and one load chamber is very small as compared with the flow cross section between the other load chamber and a discharge chamber. Precise control and fully restrained displacement of the hydraulic load is not possible in this stroke region. If further shut-off valves or braking valves are connected between the directional control valve and the hydraulic load, then a great deal of effort has to be expended for coordinating these valves in relation to the flow cross sections at the directional control valve. It is also disadvantageous that, as compared with a control piston with a blocked central position, a completely new design of the second fine control grooves is necessary.